Yes, in my first message, the ALE was connected to 8282's /G. In the second situation(RE: couldn\\\'t operate external RAM ), the /G of 8282 was connected to P1.7 for manual control.(please refer to that message for details)

And the MCU is at 12MHz.

I have tried another situation to test if MOVX and 8282 work well just now.

I placed two 1K resistors between

DATA0 & ADDR0
DATA2 & ADDR2

My system bus has DATA0-DATA7 and ADDR0-ADDR15, total of 8+16 indepandent pins. (and those +5v,gnd.......)

So I suppose that when MOVX A,@DPTR I should get the low-8-bit of the 16-bit-address in ACC.

Codes:

MOV DPTR,#00FAH ;0xFA=1111,1010(2)
MOVX A,@DPTR
MOV P1,A ;I should get 1111,1010 on P1

Result:
It works correctly... does it mean there is no problem with my bus system?

Thank you all for your help....